xserve raid upgrade to sata drives

I have a xserve raid with ultra ata seagate baracuda ES drives. Only 7 of my bays are populated. It has worked great for 2 years now. When I went to buy 7 more drives for the other half of the unit I found out the price has jumped through the roof on these ata drives because Seagate no longer makes them. Anyone have the same problem? Apparently they are oem parts made for apple so not sure if apple added some firmware to the drives or did nothing except put their logo on them. If thats the case any BaracudaES ata drive should work. Anyone know for sure?

Can the whole xserve raid be adapted to accept sata drives or are there other raids that are out there that are just as fast as the xserve raid at a fraction of this additional drive cost.

Thanks
Jim

Replying to my own message. Just found out it is not upgradeable. But the new promise raids have sata drives and the price is right. Any comments on the V-trak promise raid ?